1. Field of the Invention
The present invention relates to methods for producing optically active N-acyl-β-phenylalanine compounds. The present invention also relates to methods for producing optically active β-phenylalanine compounds. The present invention further relates to diastereomer salts of N-acyl-β-phenylalanine compounds, which are useful for preparing optically active N-acyl-β-phenylalanine compounds.
2. Discussion of the Background
Optically active β-phenylalanine compounds are known to be material for receptor antagonists and enzyme inhibitors and are compounds which are useful as intermediates for pharmaceuticals such as antithrombotic agents, etc. Known methods for the production of optically active β-phenylalanine compounds include a method in which a racemic β-phenylalanine compound is enzymatically resolved (see, for example, J. Org. Chem., vol. 63, p. 2351 (1998), as a method using penicillin acylase), and a method in which the manufacture involves asymmetric synthesis (see, for example, J. Am. Chem. Soc., vol. 116, p. 10520 (1994), as a method using an asymmetric aldol reaction), etc. However, it is difficult to obtain an optically active β-phenylalanine derivative having a high optical purity in an efficient manner. On the other hand, racemic β-phenylalanine derivatives may be relatively easily produced by synthetic means (see, for example, J. Am. Chem. Soc., vol. 51, p. 841 (1929). Thus, there has been a demand for the development of a process for the optical resolution of a racemic substance for the production of optically active β-phenylalanine derivatives.